The present invention relates to a quick hitch coupler for attachment to the mechanical hoe arm of a machine.
Quick hitch couplers facilitate the rapid change over of excavator tools/attachments in an efficient manner. Conventional tool change over's can take up to two people and can take twenty minutes. A quick hitch coupler can complete a change over in less than two minutes and can be completed by the excavator operator alone. The coupler is attached to the excavator arm where it remains continuously in place. The lower half of the coupler includes a front jaw as seen from the excavator cab so as to facilitate the gripping of the tool pin. The back area of the bottom half of the coupler as seen from the excavator cab includes a movable jaw acting as latching hooks that is generally operated by a hydraulic cylinder. The coupling of the tool or other attachment is possible by the action of placing the front jaw in one tool pin and the movable latching hooks acted on by the hydraulic cylinder grip the other pin of the tool. The tool is attached to the excavator via the quick hitch coupler. The hydraulic cylinder is activated by the excavator operator inside the cab. If the operator activates the hydraulic cylinder without having any safety feature in place and without the tool placed in a safe drop off location, it is possible that the tool may fall and cause damage, injury or death.
A semi-automatic coupler has been developed to provide a form of safety such that accidental release of the tool is not possible. In many cases the safety feature is a mechanical blocking pin inserted behind the latching hook assembly after the tool is coupled. When the safety pin is installed it is not physically possible for the hydraulic cylinder to retract, consequently holding the latching hook in situ. The tool is held in place and drop off is not possible. When tool drop off is required and intentional, the operator demounts the cab and the safety pin is removed and decoupling of the tool is now possible. The semi-automatic coupler has the problem that human intervention is required to activate the safety system. In other words, the operator has to demount the cab and physically insert the safety pin. Research and spot checks have shown that this procedure is often not complied with so to counteract this weakness in the device, a fully automatic system is used. At the instance of coupling a tool, the safety system is activated automatically. Drop off of the tool is not possible unless a predefined process and sequence of events is followed.
Accordingly, the present invention provides a quick hitch coupler having means for releasably coupling a tool to the quick hitch coupler, the means for releasably coupling a tool to the quick hitch coupler comprising tool pin engaging means on spaced apart portions of a main body of the quick hitch coupler, one tool pin engaging means having an associated latching means movably mounted on the main body of the quick hitch coupler between a tool pin locking position and a tool pin releasing position, the latching means having a locking means movably mounted on the latching means for securing a tool pin onto the latching means.